Did it work before? I'm wondering if there's a gearing issue or the wheel is on too tight. Doesn't it turn freely by hand? How's the tension of rotating the wheel relative to the other side?

DJ Thanks for your reply,

Yes it has worked correctly since new. Except for the initial software bug about the connection of the Green wire(making the sliders work L and R incorrectly) all has been good. The right track works correctly in Reverse or in a turn when the right track does not need to move in the Forward direction.
It just stopped working and during investigation of EZB wiring security and HBridge wiring security I discovered the sinked IC warm when no movement selected and blistering hot almost immediately after Forward movement selected. Movement cuts in and out after about 3-4 seconds. Appears to be internally failing due to a heat issue. Jack

Mechanically the rollers and tracks move freely.

It's failing causing a heat issue. Makes me think the motor is shorted, or a solder joint came off the motor and is shorted.

I'd first try disconnecting the leads from the hbridge that power the motor which isn't turning. Connect those leads directly to a battery and see if the motor turns.

If the motor turns, then the hbridge indeed needs replacing.

If the motor doesn't turn, then the motor may need to be replaced or examined.

The motor turns just fine in reverse via the Hbridge. Should I still check it separately?

Just disconnected the HBridge wires to the motor in question and verified that the motor turns equal RPM Forward and Reverse with just a battery across the terminals. This was done by reversing the battery polarity on the motor. Additionally the rollers/gears were verified to move freely. Hope this helps. Thanks Jack